The proposed research is designed to describe and compare the short-and long-term dental, skeletal, esthetic, and functional outcomes and efficacy of the three major alternatives commonly employed in the treatment of Class II malocclusions: 1) "growth modification" (functional appliances in children followed by a phase of adolescent treatment with fixed appliances); 2) one-step fixed-appliance therapy in adolescents and adults; and 3) combined orthodontic/surgical treatment in adults. Because of the non-specific character of Class II malocclusions, the elective nature of treatment, and the inequality of the risks involved in various treatment alternatives (e.g., surgery as opposed to orthodontics), it is concluded that ethical, prospective trials would of necessity be severely limited in scope. The present research, therefore, will employ a longitudinal, partially retrospective design in which steps are taken to eliminate the types of bias that often compromise case-control studies: selection will be independent of outcome and will be designed to identify overlapping samples of patients for whom there is empirical evidence of uncertainty concerning the optimal choice of therapy. This approach will minimize susceptibility bias and thus will permit clinically meaningful comparisons between pairs of logical alternatives (e.g., extracting versus non- extraction edgewise or adult orthodontics versus surgery) in patients for whom either approach might commonly be employed. Because there is controversy surrounding the effect of both fixed and functional appliances on facial growth and occlusal development, comparable samples of untreated Class II subjects will be employed to differentiate between normally occurring changes and those due specifically to treatment. In addition to the description and comparison of treatment changes and subsequent relapse, the resulting data will provide insight into the predictability and propriety of contemporary therapeutic goals, the perceived utility of various treatment outcomes and the anatomical bases for the esthetic preferences of Blacks and whites. Because the present studies will draw from extensive pools of carefully executed and routinely documented treatments, it is probable that they can be conducted as outlined and completed within the initial period of support.